Two types of tonometers, indentation and applanation, were compared for their ability to accurately measure intraocular pressure (IOP) in rabbit eyes. Manometric measurements were made by vitreous cannulation to minimize the physiological and technical disadvantages associated with simultaneous aqueous chamber manometric measurement and tonometric pressure recording. Each of ten pressure levels from 15 to 60 mm Hg were measured by two independent observers. At most pressure levels, neither instrument accurately measured IOP as determined by vitreous chamber cannulation. The two instruments, however, responded similarly to each other at all pressure levels tested. In every instance, mean measurements made by applanation tonometry were lower than those recorded by indentation tonometry. Graphs have been prepared for use in converting measurements taken from rabbit eyes using these instruments to manometric IOP.
Leaders FE, Hodges JW, Fortenberry B. Indentation and Applanation Tonometry in RabbitsA Comparative Study. Arch Ophthalmol. 1969;82(2):239–244. doi:10.1001/archopht.1969.00990020241018